Polymer catalysts

ABSTRACT

AN IMPROVED CATALYST COMPONENT IS PREPARED BY REACTING A HEAVY TRNSITION METAL HALIDE, SUCH AS TITANIUM TETRACHLORIDE, WITH AN ALUMINUM ALKYL, SUCH AS ALUMINUM TRIETHYL, UNDERR SPECIFIC TEMPERATURE, TIME AND MOLE RATIO CONDITIONS. THE IMPROVED CATALYST COMPONENT IS THEN ACTIVATED WITH AN ALUMINUM ALKYL TO FORM A CATALYST USEFUL FOR POLYMERIZING OLEFINS.

United States Patent 27,940 POLYMER CATALYSTS Arthur W. Langer, Jr.,Watchung, and Erik Tornqvist,

Roselle, N.J., assignors to Esso Research and Engineering Company NoDrawing. Original No. 3,032,511, dated May 1, 1962,

Ser. No. 858,861, Dec. 11, 1959, which is a continuation-in-part ofabandoned application Ser. No. 629,488, Dec. 20, 1956. Application forreissue Apr. 30, 1964, Ser. No. 377,154

Int. Cl. B01j 11/84; C08]? 3/04, 3/10 U.S. Cl. 260-935 17 Claims Matterenclosed in heavy brackets appears in the original patent but forms nopart of this reissue specification; matter printed in italics indicatesthe additions made by reissue.

ABSTRACT OF THE DISCLOSURE An improved catalyst component is prepared byreacting a heavy transition metal halide, such as titaniumtetrachloride, with an aluminum alkyl, such as aluminum triethyl, underspecific temperature, time, and mole ratio conditions. The improvedcatalyst component is then activated with an aluminum alkyl to form acatalyst useful for polymerizing olefins.

The present invention relates to the preparation of polymers and thecatalysts used to prepare them. Specifically it concerns catalysts whichpolymerize olefins, especially alpha olefins.

This application is a reissue of Pat. No. 3,032,511, which is acontinuation-in-part of Ser. No. 629,488, filed Dec. 20, 1956 and nowabandoned.

It is known that olefins, such as ethylene, propylene, etc. can bepolymerized at relatively low pressures by using various combinations ofaluminum compounds and reducible heavy metal compounds, e.g. titanium,zirconium and iron. Among the most active types of catalyst for thisreation are combinations of trialkyl aluminum or dialkyl aluminum halidewith a titanium tetrahalide. For instance, excellent results areobtained by using combinations of triethyl aluminum or diethyl aluminumchloride with titanium tetrachloride, made by simply mixing the catalystcomponents at atmospheric temperature in suitable solvents. Thesecatalysts have been found to afford high yields of high molecularweight, solid polymers, especially with monomers, such as ethylene andpropylene, as well as other olefins, even at pressures as low asatmospheric.

These catalysts may be prepared by reacting an aluminum compound with aheavy metal compound at a temperature between about 20 and 90 C.Generally the product is a brown, amorphous catalyst which is unstableand tends to make a less crystalline polymer when activated withadditional aluminum compound. If it is desired to make a highlycrystalline polymer, for instance an isotactic polypropylene, thecatalyst should have a crystalline structure. In the case of titanium,the crystalline titanium trichloride is identified by its purple orviolet color and its characteristic X-ray diffraction pattern, which isdifferent from the pattern given for the alpha form previously known.While it is known in the art that the alpha form of purple crystallinetitanium trichloride may be prepared by reacting titanium tetrachloridewith titanium at a temperature between about 400 and 500 C. under apressure of about 10 to 50 atmospheres, or by reacting the tetrachloridewith hydrogen in the presence of a glowing tungsten filament, there isno known method for preparing the instant crystalline form usingorganometallic compounds, e.g. aluminum triethyl, as the reducing agent.

It has now been discovered that highly crystalline Re. 27,940 ReissueclMar. 12, 1974 polymerization catalysts, as well as catalysts ofintermediate crystallinity, may be prepared at relatively lowtemperatures by reacting a metallic reducing compound With a reducibleheavy metal compound under critical conditions which are hereinafterdisclosed.

In practicing one embodiment of the present invention the theoreticalamount of a reducing organo-metallic compound, such as aluminumtrialkyl, is reacted in a suitable inert diluent with a reducible heavymetal compound, such as those found in groups IV and VI and VIII of theperiodic system, at a temperature above about C. but less than about 300C. for from a few minutes, e.g. about 5 minutes, up to about 20 hours.The reaction product may then be activated with additionalorgano-metallic at a lower temperature, that is between about 0 and 100C. The resulting catalyst is either completely or partially crystallineand, depending upon the severity of the pretreatment, forms at leastpartially isotactic polymers with alpha olefins, such as propylene, andin most instances polymers which are highly isotactic.

The reaction conditions should be chosen so that a catalyst of thedesired degree of crystallinity is obtained. This is preferably achievedby pretreating at a temperature between about and 200 C. and, in thecase of titanium halides and aluminum alkyls, the best results areobtained at temperatures between about and 175 C., the optimumtemperature being dependent of reaction time, concentration of reactantsand type of solvent employed. The time required for the reaction ispreferably between about 20 minutes and 2 hours.

Generally the reaction is run in a liquid medium, especially when onereactant is a solid at reaction temperature. However, when bothreactants are liquids or gases, the pure compounds may be mixed in anysuitable manner which will allow convenient handling and recovery of thesolid, reduced, heavy metal compound. For example, either gaseous oratomized liquid aluminum triethyl may be reacted with hot vapors oftitanium tetrachloride by intimately mixing them in the presence orabsence of an inert gaseous diluent. In this embodiment the crystallineTiCl product is handled and recovered conveniently as fluidized solid.

When the reaction is carried out in the liquid phase an inert liquiddiluent is preferred. Excellent results have been obtained usingparafiins, isoparaflins, naphthenes and mixtures thereof, although inmany instances aromatics, halogenated parafiins, halogenated aromatics,perfluoro compounds and various other diluents may be used provided theydo not react chemically with either catalyst component or with the finalcatalyst product. The boiling point of the diluent is not critical aslong as liquid phase can be obtained by means of elevated pressure. Forexample, n-heptane has been used at temperatures above its boiling pointunder suitable pressures to maintain a liquid phase, whereas decane wasfound to be satisfactory at atmospheric pressure up to about C. Higherboiling diluents have been used successfully at even higher temperaturesand atmospheric pressures. The concentration of the reactants should bebetween about 5 to 100 grams/liter of diluent, preferably about 10 to 50grams/liter.

Because these catalysts are easily poisoned, the crystalline catalystintermediate should be prepared under an inert atmosphere, such as drynitrogen. Other suitable inert materials include helium, argon, hydrogenand hydrocarbons such as methane and ethane.

The mol ratio of reactants in the pretreatment stage should be such thatthe reducible compound is reduced to the next lower level, e.g. TiCl, toTiCl with preferably the stoichiometric amount of reducing agent basedon the maximum theoretical reducing capacity of the latter. If an excessof reducing agent is used, the product will be over-reduced and resultin an unstable amorphous form which has a low activity and yields a lesscrystalline polymer. On the other hand, if too small an amount ofreducing agent is employed, only a portion of the reducible substancewill be in the desired stable form and the unreduced material will besusceptible to over-reduction during the polymerization. Thus the molratio of reducing agent/reducible compound must be very carefullycontrolled to meet these specific requirements. For example,conventional catalyst preparations employ ratios of 0.5/1 or higher ofaluminum triethyl to titanium tetrachloride, whereas it has now beenfound that by using ratios of about 0.30 to 0.36/1, and preferably0.33/1, over-reduction is avoided when pretreatment temperatures aboveabout 100 C. are employed. Similarly when other metal alkyl compoundsare used, such as aluminum ethyl dichloride and aluminum diethylchloride, the stoichiometrical ratio of alkyl metal compound to TiCl,,based on the maximum theoretical reducing capacity of the formercompounds, should be employed. Previously, very weak reducing agents,such as aluminum ethyl dichloride were thought to be incapable ofreducing TiCl, to produce an active catalyst. However, at temperaturesabove about 100 C. aluminum ethyl dichloride is capable of reducingTiCl, to TiCl which can be used for the polymerization of alpha olefins,such as propylene, when activated with aluminum triethyl or aluminumdiethyl chloride.

Whereas the minimum ratio of alkyl metal compound to TiCl, that can beadvantageously used for the catalyst preparation is determined by themaximum reducing capacity of the alkyl metal with respect to theformation of TiCl the corresponding maximum ratio is determined by theability of the alkyl metal to further reduce TiCl to TiCl Thus the ratioof alkyl metal compound to reducible compound must be carefully adjustedso that after the desired reduction has taken place no alkyl metalcompound is present which is capable of causing further reduction. Forinstance, aluminum diethyl chloride and aluminum ethyl dichloride willnot reduce titanium trichloride at temperatures of below about 70 and100" C., respectively. Their ability to accomplish this reductionincreases, however, with increasing temperature. This means that attemperatures above 100 C. in the aluminum triethyl/titaniumtetrachloride system, all three alkyl groups will be active in thereduction. Thus in this system it is critical to use a molar ratio ofabout 0.30/l to 0.36/1. n the other hand, only one of the alkyl groupsof aluminum triethyl is active when the reduction is carried out at roomtemperature. Under such conditions it is then desirable to mix an AlEt/TiCl mol ratio of about l/l. Obviously the optimum ratio is dependentupon the number of active alkyl groups and will vary with the number ofsuch groups in the compounds used. For instance, in the case of analuminum diethyl chloride/ titanium tetrachloride system, or a zincdiethyl/titanium tetrachloride system, the mo] ratio should be about 0.5when the reduction is carried out at a temperature at which both of thealkyl groups are active. Similarly, the type of transition metalcompound to be reduced may have an influence on the optimum ratio.

A large number of reducing compounds can be used to pretreat andactivate the heavy metal compound. Among the most valuable are alkyl oraryl aluminum compounds, especially trialkyl aluminum compounds, such astriethyl aluminum, tripropyl aluminum, triisobutyl aluminum, triphenylaluminum, etc. and dialkyl aluminum compounds such as diethyl aluminumhalides, diethyl aluminum chloride in particular, dipropylhalides,diisobutyl halides, etc. However, as previously mentioned, monoalkylaluminum compounds can also be used. Generally, in addition to trialkylor triaryl aluminum, organo aluminum compounds carrying two or at leastone hydrocarbon radical, as well as one or two electron attractinggroups, such as halogen, alkoxy, organic nitrogen or sulfur groups, etc.may be used. Instead of the alkyl or aryl aluminum compounds, thecorresponding hydrides or mixed hydrides of aluminum may be used.

Other suitable reducing materials include organometallic compounds ofelements of the I, II and III groups of the periodic system as well ashydrides or mixtures of alkyl or aryl compounds and hydrides of theseelements. In addition to this alkali and alkaline earth metals as wellas certain other metals such as aluminum which have sufiicientreactivity at the temperatures employed, may be used in the reduction.Whatever material is used for the reduction, it is important that theratio between reducing agent and transition metal compound be adjustedso that over reduction or under reduction will be prevented.

Reducible heavy metal compounds suitable for the purposes of theinvention include such inorganic compounds as the halides, oxy-halides,complex halides, oxides, hydroxides, and organic compounds such asalcoholates, acetates, benzoates, and acetyl acetonates of thetransition metals of the IV, V, VI and VIII groups of the periodicsystems, e.g. titanium, zirconium, hafnium, thorium, uranium, vanadium,niobium, tantalum, chromium, molybdenum, tungsten and manganese, as wellas iron and copper. The metal halides, particularly the chlorides, aregenerally preferred, titanium, vanadium, and zirconium being the mostactive of these metals. The following heavy metal compounds are readilyreducible requiring only low activation temperatures: titaniumtetrachloride, titanium tetrabromide, vanadium tetrachloride, zirconiumtetrachloride, zirconium tetrabromide and zirconium acetylacetonate.

The reacting compounds may be mixed in an inert diluent at thetemperature chosen for the pretreatment, or they may be mixed at a lowertemperature where the chance of over reduction is lower. Under thelatter conditions, the TiCl first formed, is converted into thepurpleviolet crystalline form by raising the temperature to asufficiently high level. For instance, suitable proportions of triethylaluminum and titanium tetrachloride may be mixed in an aliphatichydrocarbon solvent at about 60- C. or even as low as room temperatureor lower. The precipitate of TiCl formed is, upon heating in the diluentto about C. or higher for a sufficiently long time, converted to thecrystalline form.

The comopsition of the catalyst intermediate may vary according to thereactants and the reaction conditions. For instance where the heavymetal compound is a titanium halide and the reducing compound is analuminum alkyl there may be between about 0.3 to 1 atom of aluminum peratom of titanium depending on the number of alkyls in the aluminumcompound. To illustrate this, where an aluminum alkyl dichloride is usedthe atomic ratio of Al/Ti in the intermediate should be 1 to 1, where analuminum dialkyl chloride is used it should be 0.5 to 1 and where analuminum trialkyl is used it should be 0.33 to 1.

The catalysts so pretreated are activated, in the presence or absence ofthe alpha-olefin to be polymerized, by the addition of further amountsof alkyl metal compounds, trialkyl aluminum compounds in particular. Theamount of alkyl metal needed for activation will depend upon theparticular pretreated catalyst intermediate and the pressure used duringthe polymerization. If the polymerization pressure is approximatelyatmospheric, the greatest activation is obtained with trialkyl aluminumcompounds, e.g. triethyl aluminum and tripropyl aluminum. The amount oftrialkyl metal compound added should be such that, after it has reactedwith compounds such as AlCl to form the corresponding dialkylhalide,about one mol of unreacted trialkyl aluminum remains in the system foreach mol of TiCl in the pretreated catalyst. For instance, if a trialkylaluminum is employed, both to reduce TiCl, and activate the catalystintermediate a total Al/Ti molar ratio of about 1.5 to 3.0, andpreferably about 2.0, should be used.

The total molar ratio, including any aluminum compound used in thepretreatment step, of the aluminum alkyl compound to titanium halide inthe catalyst has an influence on the molecular weight of the polymerobtained. In general the total Al/Ti ratio should be between about 1 and12. The higher this ratio is, the higher will be the molecular weight ofthe polymer. In some instances it may be desirable to activate thecatalyst with a different metal alkyl compound than was used to reducethe heavy metal compound.

The polymerization process may be carried out under conventionalconditions used in the low pressure polymerization of olefins. Theseconditions depend somewhat on the specific olefin involved and on thetype of polymer desired. Propylene is the preferred olefin althoughother olefins, such as ethylene, butylene, etc. may be used alone or incombination. In the case of propylene, the polymerization may be carriedout by intimately contacting gaseous propylene with the catalyst, forexample, by bubbling the propylene into a suspension of the catalyst inan inert solvent or diluent. Neither the polymerization temperature northe polymerization pressure is particularly critical, but it ispreferred to operate at temperatures of about to 110 C., and especiallybetween about 40 C. to 90 C.

Pressures ranging anywhere from subatmospheric to 250 atmospheres havebeen used heretofore. While this full pressure range may be employedwith the catalysts of the present invention, atmospheric pressure hasbeen found to be quite satisfactory for use with the present catalysts.Accordingly, an advantage of this invention is that generally thepolymerization can be carried out at substantially lower pressures thanare required to accomplish similar results with conventionally preparedcatalysts. This is attributable to the high reactivity and other uniqueproperties of these new catalysts.

The polymerization reaction is preferably carried out while stirring inbatch or continuous operation. When operating batchwise, olefinintroduction is continued until the catalyst is wholly or partiallyexhausted and the reaction starts to cease. In order to permit stirringeven after the formation of substantial amounts of solid poly mer,solvents or diluents may be used. These diluents, which should be liquidat the operating conditions, include aliphatic, hydroaromatic andaromatic hydrocarbons, such as pentane, hexane, heptane, higherparaflins, isoparaffins, cyclohexane, tetrahydronaphthalene,decahydronaphthalene, benzene, xylene, halogenated aromatichydrocarbons, e.g. monoor di-chlorobenzenes, and mixtures of these andother diluents. Sufiicient pressure may be applied during the reactionto maintain the lower boiling diluents in a liquid state. The polymerconcentration in the reaction mixture may reach 10 to 40 wt. percent,although lower concentrations can of course be used.

The amount of catalyst employed may vary within the limits dependingsomewhat on the purity of the olefin feed. Proportions as small as 0.1part by Weight of catalyst per 1,000 parts by weight of olefin aresuflicient if the feed is pure. With olefin feed streams containing upto about 0.01% of water, carbon dioxide or certain other oxygenatedcompounds, catalyst proportions of about 0.5 to 5 wt. percent areusually adequate.

Upon completion of the polymerization reaction, the catalyst may becompletely deactivated, e.g., by the addition of an alcohol, such asisopropyl alcohol or n-butyl alcohol, in amounts of about to 100 timesthe amount of catalyst used. The reaction slurry may then be filtered,the filter cake reslurried in a catalyst solvent, such as dry,concentrated alcohol at about 50 to 100 C. for to 60 minutes, filteredagain and the filter cake dried, preferably under reduced pressure. Ashresidues in the polymer are reduced below about 0.05% by this procedure.If necessary, the ash content may be further reduced by aqueous acidtreatment, etc. according to methods well known in the art, or by usingchelating agents, such as acetylacetone.

The polymers produced according to the present invention have molecularweights in the range of about 100,- 000 to 300,000 or even as high as3,000,00 as determined by the intrinsic viscosity method using the I.Harris Correlation (J. Polymer Science 8,361, 1952). They have a highdegree of crystallinity and a low solubility in nheptane.

The invention will be best understood by referring to the followingexperimental data and specific examples.

EXAMPLE 1 The critical nature of the mol ratio of the reactants in thepreparation of crystalline catalysts at temperatures between about and300 C. is shown by the following series of tests in which titaniumtetrachloride and aluminum triethyl were reacted in pure n-decane C. for1 hour using Al/Ti ratios of 1.0, 0.5, and 0.33, respectively.Polymerizations were run with these catalysts in a batch reactor, usingxylene as the diluent, at atmospheric pressure and temperatures between60 and 100 C. In each case the Al/Ti mol ratio was adjusted to 2.0 forthe polymerization reaction.

It is evident that over reduction caused by the high Al/Ti ratiosgreatly decreases catalyst activity. The over reduction of titanium isshown by the dark color (TiCl is black), whereas at a 0.33 ratio, thereduced titanium had a purple-red color which is indicative ofcrystalline TiCl The 0.33/1 Al/Ti ratio under these pretreatmentconditions results in complete conversion of TiCl to TiCl without overreduction. Furthermore, crystalline TiCl is more stable than amorphousTiCl toward further reduction and allows better reproducibility. Byvarying the temperature, time and concentration of the reactants, therate of crystallization, the degree of crystallinity and the particlesize of TiCl can be varied to some extent. As will be shown in thefollowing example, these variables afi'ect polymer properties andcatalyst activity.

EXAMPLE 2 Increased catalyst crystallinity may be obtained by increasingthe pretreatment temperature, time and concentration of reactants,provided the stoichiometric ratio of reducing agent to heavy metalcompound is used to prevent over reduction. In Table II below, data aregiven which show the effect of the pretreatment temperature on thetitanium trichloride and the corresponding effects of the resultingcatalyst on the polymers properties. The reactants in each case werealuminum triethyl and titanium tetrachloride.

The increased crystallinity of TiCl obtained by increasing the reactiontemperature is illustrated by X-ray analysis and decreased surface area,as well as the purple color of the catalyst.

The analysis of the catalyst solids in Table II demonstrates theincreasing reduction capacity of the triethyl aluminum with increasingtemperature. Thus at temperatures below 135 C. only part of the aluminumfrom the triethyl compound is incorporated in the solid catalyst,whereas at 135 C. almost all aluminum is incorporated in the TiClcatalyst as AlCl indicating that all the ethyl groups have been activein the reduction. The high degree of crystallinity in the polypropyleneruns D and E, is shown by the increased heptane insolubles, tensilestrength and melting point, together with the decreased elongation.Polymers of this type are desirable in the field of flexible plastics,semi-rigid molded articles, pipes, etc.

The activity of the catalyst varies with method of preparation and thekind of diluent employed. As higher temperatures are used to prepare theTiCl it becomes The catalyst prepared in xylene was considerably lessactive than that one prepared in n-decane in spite of a larger surfacearea. The catalyst analysis show that little aluminum was left in thesolid catalyst after treatment in xylene at 135 C. which may be onereason for its I n s V I n a n u s more crystalline and resistant toover reduction during a lower activity. Additionally, it is believedthat the gamma the polymerization reaction. The advantages which cancrystalline form is more active than the beta crystalline be derived byusing two different diluents may be seen form. by comparing runs D andE, where with the same cat- The gamma crystalline form as produced bythe present alyst preparation different degrees of catalyst activity, 1)process has been found to have the X-ray difiraction polymercrystallinity, etc. were obtained. pattern shown below.

TABLE II Run No A B C D E Catalyst pretreatment:

AlEt TiChratlo 1 1 0.5 0.3a 0.33.

Temperature, C 70 100 135 135.

Time, hours 0.1 l 1 l 1.

Diluent n1ieptane n-Heptane.... n-Decaue n-Decane n Decane.

Analysis of dry catalyst:

t of

Color Light brown Brown Dark brown Purple Purple.

X-rny relative crystal Amorphous... Amorphous... Slightly crystalline...Crystalline.. Crystalline.

Surface area, rnJ/g 257 30.5 30.5. Polymerization (All'li=2):

Diluent n-Heptane n-Heptane n-Heptane n-Heptane. Xylene.

Avg. temperature, C 40 40 90.

Rate. g./lir./g l6 28 35 14 24. Totalheptaneinsolubles, percent 35 55 0063 08. Alcohol 1nsoluble polymer:

M01. wt.X10 51 107 73 145.

Specific gravity, g./ce 0.805 0.872 0.887 0 87 0.885.

Tensile. p.s.l 1,570 3,640 4,650.

Elongation, percent 25.

Softening p0int. C 123 1 10 160 160.

Melting point, C 155 153 163 170 173.

I TiCl was added to pretreatment diluent and heated to 80 C. at whichtime the AlEti (aluminum tn'ethyl) was added. The temperature was thenrapidly raised to the pretreatment temperature. In all other cases theAlEt; was added at pretreatment temp.

1 Pretreated catalyst was added to the reaction diluent and AlEt;presaturated at 10 C. with 0 11 a 2/1 mixture of isopropy]alcohol/diluent.

EXAMPLE 3 The importance of using a proper diluent for the catalystpretreatment is demonstrated by the data in Table III.

TABLE 111 Run No E F Catalyst pretreatment:

AlEt lIiClt ratio 0.33 0.33. Temperature, C 135. Time, hour 1 1. Dilucntn-Decane Xylene. Analysis of catalyst solids:

Ato

. 0.06. 3.08. C Brownlsh black. Xray difiraction pattern- TifClg-gammaTiCl; beta form.

0111}. Surtacenrea, 111. 1g 30.5 103. Polymerization (Al/Ti-Z): 1

Diluent 90 n;- 15 Totalheptaneinsoluhles,percent.... 68 49. Properties01 alcohol insoluble polymer: 3

MolecularweightXlO- 89.

Density, gJmI 0.873. Elongation, percent" Tcnsile strength, p.s.lSoltening point. 152. Melting point 173 165.

1 TiCh was added to pretreatment diluent and heated to 80 C. at whichtime the AlEti was added. The temperature was then rapidly raiscd to thepretreatment temperature. In all other cases the AlEt was added atpretreatment temperature.

1 lretreated catalyst was added to the reaction diluent and AlEt;presuturated at 10 C. with CsHo.

I 211 misture oi isopropyl alcohol/diluent.

d-Spacz'ngs in angstrom units: Relative intensity A series ofexperiments was performed in order to show the critical nature of themole ratio of the reactants as well as the importance of using asufliciently high temperature of pretreatment for obtaining a highlystable and crystalline solid catalysts component. The catalyst Wasprepared by reacting 4.4 mmole (0.85 g.) of V01 in 50 ml. of a suitablediluent (n-heptane or n-decane) with varying amounts of AlEt at 70 C. orC. for 1 hour as shown in Table IV. The pretreated catalyst slurry wasthen added to a stirred batch reactor containing 950 ml. of n-heptanesaturated with propylene at 10 C. and containing the amount of AlEtneeded for bringing the Run No G Catalyst pretreatment:

A.Et3/VCI Temperature, C. Time, hours..- Diluent Polymerization(AlfV=2):

Avg. temperature, C 47 Rate, g./hr.lg Waxy polymer, percent Propertiesof solid polymer:

oi weight-10' Density, g./rnl Tensile strength, p.s. Elongation, percentI VCli was added to the pretreatment diluent and heated to 80 C. atwhich time the AlEti (aluminum triethyl) was added. The temperature wasthen rapidly raised to the retreatment temperature.

b Pretreated catalyst was ad ed to the reaction diluent and AlEt;presaturated at 10 C. with CsHa.

Semi-amorphous polymer remaining in solution at 50 C. after 2 volumes ofisopropanol had been added to precipitate the solid polymer.

6 According to the Harris Correlation (J. Polymer Science, 8,361(1952)).

It can be seen from Run G compared to Runs H and I in Table IV thatpretreatment at 70 C. even at an Al/Ti mole ratio of 1.0 yields a muchless active and more unstable catalyst than pretreatment at 150 C.Pretreatment at a lower Al/Ti ratio than 1.0 at 70 C. gives even a lessactive catalyst.

The importance of using a mole ratio between AlEt and VCl, of about 0.33when pretreating at a temperature at which all the alkyl groups of theAlEt may take part in the reduction is shown in runs H and I. Anincrease of this ratio from 0.33, which is the stoichiometric ratio, to0.5 results in a decrease in polymerization rate from 42.9 g./hr./g. to20.5 g./hr./g.

EXAMPLE 5 The importance of using a sufficiently high temperature ofpretreatment for obtaining a crystalline and highly stable solidcatalyst component was further demonstrated in the series of runsrecorded in Table V. The catalysts were pretreated according to themethod described in Example 4 and at the Al/Ti mol. ratios andtemperatures indicated in Table V. The polymerizations were then carriedout isothermally at 60 C. for 2 hours in 1 l. of xylene diluent usingthe same equipment and general procedure as described in Example 4.

TABLE V.POLYMERIZA'TION OF PROPYLENE WITH SPLIT PRETREATED VCIrAlEtsCATALYSTS [2 1. glass batch unit, 1 l. xylene diluent] Run No J K LCatalyst pretreatment:

C1i,g 0. B5 0.85 I) 85. AlEis g... 0.5- 0. 17.

Al/V ratio... 1.. 0.33. Temperature, 70-. 100 150. a Time, hours. 1 1 l.Diluent n-Heptane. n-Decane n-Decane Reaction conditions:

AlEts separately added, g 0.5 0.75 0.83. Al/V ratio 2. Avg. polym.temp., Run length, hours 2 2 Results:

Max. absorption rate, mlJgJmin. 0 Polymer yield, g 1. 9 Waxy polymer,percent Catalyst eificiency, g./g 1. 0 Pro erties of solid polymer:

I01. WeightXIO- 170 290 200. Density, g./ml. .8838"--- 0. 8843.

C 150/l5fi 157/162.

l V614 was added to the pretreatment diluent and heated to 80 C. atwhich time the AlEt; (aluminum triethyl) was added. The temperature wasthen rapidly raised to the pretreatment temperature.

Semi-amorphous polymer remaining in solution at 50 C. aiter 2 volumes ofisopropanol had been added to precipitate the solid polymer.

1; 5r ga-cording to the Harris Correlation (J. Polymer Science, 8, 361,

Soft. pt./M P

Two experiments were performed which showed that a highly crystallineand stable solid TiCl catalyst component capable of polymerizingpropylene to a polymer of good properties can be prepared by using adialkyl aluminum halide as the reducing agent at the preferred Al/Tiratio previously described. In Table VI, Run M, AlEt F was used both asreducing agent in the split pretreatment and as activator in thesubsequent polymerization, whereas in Run N, AlEt F' was used only asthe reduciug agent and AlEt as the activator. The split pretreatment wascarried out at 150 C. essentially as described in Example 4. Thepolymerizations were carried out isothermally at 75 C. for 2 hours in 1l. of a 9/1 xylene/n-decane diluent using the same equipment and generalprocedure as described in Example 4.

Polypropylene of good physical properties was obtained in bothexperiments. However, the yield was much higher when AlEtg was used asthe activator. In this case, Run N, a polymer of unusually highcrystallinity (density=0.9009 g./ml. with only 0.4% waxy polymer beingrejected) was obtained at a good rate. This proves that a highlycrystalline catalyst component can be obtained according to the methodof this invention using an alkyl aluminum halide as the reducing agent.It also demonstrates the superiority of aluminum trialltyls asactivators for the subsequent polymerization reaction.

TABLE VI.POLYMERIZATION OF PROPYLENE WITH SPLIT PRETREATED TiClr-AlEtzFCATALYSTS [2 l. glass batch unit, 900 ml. xylene and ml. ndeeane asdiluent] Run No M N Catalyst pretreatment:

TiCh, g 1.90 190 AlEtgF, g- 0.52--. Al/Tiratio- 0.5.... Temperature, C150 I Time, hours 1 1. Diluent n-Decane u-Decane. Reaction conditions:

Al alkyl separately added:

Type AlEt F AlEiia. Weight,g 1.56 1.71. Al/Ti ratio 2 2. Polymerizationtempera- 75 75.

ture, 0. Run length, hours 2 2. Results:

Magi. absorption rate, ml./g.l 55 200.

n. Polymer, yield, g 9.0 50.9. Waxy polymer, percent 5 6 0.4.

Catalyst efficiency, g./g 2:20 Properties of solid polymer: Moi.weightXlO- I TiCh was added to the retreatment diluent and heated to 80C. at which time the AlEtaF iethyl aluminum fluoride) was added. Thetern rature was then rapidly raised to the pretreatment temperature.

b elm-amorphous polymer remaining in solution at 50 C. after 2 volumesof isopro anol has been added to precipitate the solid polymer.-

' According to t e Harris Correlation (J. Polymer Science, 8,361,(1952)).

Although the catalyst preparations in the examples were done batchwiseand were used in batch runs it is obviously within the scope of thisinvention to utilize batch preparations in continuous polymerizations orto accomplish the batch type preparation by pretreating in two stages orin pipe flow to obtain the effect of batch pretreatment. The inventionis not to be limited to the specific examples given. The relativeproportions of the materials used and the reaction conditions may bevaried within the limits indicated in the specification to obtainproducts of varying characteristics.

What is claimed is:

1. A process for preparing a crystalline catalyst material whichcomprises reacting a heavy transition metal halide of a metal selectedfrom groups IV and V of the Periodic Table with an aluminum alkyl at atemperature in the range of 120200 C. for a period of time from aboutminutes to 20 hours to reduce the metal compound to its next lowervalence; the mo] ratio of aluminum alkyl to metal halide being in therange of 0.30/1 to 0.36/1 when said aluminum alkyl contains three activealkyl groups, the ratio being about 0.5/1 when said aluminum alkylcontains two active alkyl groups, and said ratio being about 1/1 whensaid aluminum alkyl contains one active alkyl group.

2. The process of claim 1 wherein said heavy transition metal halide istitanium tetrachloride and said reducing metal-containing material istriethyl aluminum.

3. The process of claim 1 wherein said heavy transition metal halide isvanadium tetrachloride.

4. The process of claim 1 wherein the temperature is in the range ofabout 120 to 200 C. and the period of time is in the range of 20 minutesto 2 hours.

5. The process of claim 1 wherein one mole of titanium tetrachloride isreacted with about 0.5 mole of dialkyl aluminum halide.

6. The process of claim 1 wherein one mole of vanadium tetrachloride isreacted with about 0.5 mole of dialkyl aluminum halide.

7. The process of claim 2 wherein the ratio of triethyl aluminum totitanium tetrachloride is about 0.33/1.

8. A process of preparing a crystalline catalyst intermediate comprisingreacting one mole of titanium tetrachloride with about 0.33 mole oftrialkyl aluminum in the presence of an inert liquid diluent, heatingthe reaction product to a teperature in the range of about 135 to 175 C.for from about 20 minutes to 2 hours to reduce the titaniumtetrachloride to crystalline titanium trichloride.

9. The process for preparing crystalline catalyst intermediatecomprising reacting of one mole of vanadium 40 tetrachloride with about0.33 mole of trialkyl aluminum in the presence of an inert liquiddiluent, heating the reaction product to a teperature in the range ofabout 135- n-decane. 15 14. The process of claim 12 wherein the diluentis n-heptane.

15. The product of claim I wherein the transition metal halide wastitanium tetrachloride.

16. The product of claim 1 wherein the transition metal halide wasvanadium tetrachloride.

17. A method for polymerizing alpha olefin monomers which comprisescontacting said monomers with the catalyst coposition of claim 10.

5 References Cited The following references, cited by the Examiner, areof record in the patented file of this patent or the original patent.

UNITED STATES PATENTS 2,862,917 12/1'95 8 Anderson et al. 252-429 A2,939,846 6/1960 Gordon et a1. 252-429 A 2,985,617 5/1961 Salyer et a1.252429 A 3,058,963 10/1962 Vandenberg 252-429 A 3,109,822 11/1963Kaufman et al. 252-429 C 3,141,872 7/1964 Natta et al. 252-429 A8,839,518 6/1958 Brebner.

2,874,153 2/1959 Bowman.

2,893,984 7/1959 Seelbach et al.

PATRICK P. GARVIN, Primary Examiner US. Cl. X.R.

'252429 A, 429 C; 26094.9 B

